African American spirituals, usually with a Christian religious theme, were originally monophonic and a cappella and were antecedents of the blues. The terms Negro spiritual, Black spiritual, and African-American spiritual, jubilee, and African-American folk songs are all synonymous. Spirituals sometimes provided comfort and eased the boredom of daily tasks. They were an expression of spiritual devotion and a yearning for freedom from bondage. Sometimes they were a means of releasing pent up emotions and expressing sorrow. Frederick Douglass, a former slave wrote, "I did not, when a slave, fully understand the deep meaning of those rude and apparently incoherent songs. I was, myself, within the circle, so that I could then neither hear nor see as those without might see and hear. They breathed the prayer and complaint of souls overflowing with the bitterest anguish. They depressed my spirits and filled my heart with ineffable sadness...The remark in the olden time was not unfrequently made, that slaves were the most contented and happy laborers in the world, and their dancing and singing were referred to in proof of this alleged fact; but it was a great mistake to suppose them happy because they sometimes made those joyful noises. The songs of the slaves represented their sorrows, rather than their joys. Like tears, they were a relief to aching hearts.